Use of third-party tools that misrepresent their identity to Anthropic’s servers, attempt to route third-party traffic against subscription limits, or otherwise violate applicable terms or policies is prohibited and such use may be enforced against.
[1] https://support.claude.com/en/articles/13189465-logging-in-t...
Without the billing tag, third-party tools get silently reclassified from your plan allocation to overage (pay-per-token) after ~1 hour. You're not getting free access — you're getting charged extra for access you already paid for.
The fingerprint injection exists because Anthropic's infrastructure uses it to route billing. If they exposed a proper API for Max subscribers, this wouldn't be necessary.
It's irrelevant if you're paying them. They say clearly 1P apps are ok; 3P apps are not. Yours is 3P, so you're breaking the ToS.
Will they care? Probably not. At least not until you become popular enough to show up in their dashboards. So you should be fine for a whole, until you cross some threshold and they decide it's time to close the loophole.